1. Field of the Invention
The present invention relates to a print processing method of generating print data to be transmitted to an image output device that outputs image data, and an information processing apparatus that implements the method.
2. Description of the Related Art
In print processing performed by printer drivers for high-function printers, when a drawing instruction is provided from an operating system (OS) to the printer driver, the drawing instruction is replaced with corresponding drawing commands in a page description language before data is transferred to the printer. The Page Description Language will be hereinafter abbreviated as PDL and the method that uses PDL will be referred to as PDL mode. PDL-mode in general has the advantages that it reduces the amounts of data and therefore allows printers to perform processing fast as compared with low-function printers (such as dumb printers, video printers) that do not have PDL and accept only bitmaps as input.
As personal computers become faster and application programs become more sophisticated in functionality, a wider variety of graphical representations are contained in documents such as presentation handouts. Consequently, the amount of data handled in PDL mode is increasing and even high-function printers have become often slower than low-function printers accordingly.
For example, the processing speed of a printer can become slow when objects specified in drawing instructions provided from an OS are small in size but large in number. In such cases, the total throughput can sometimes be increased by rendering the data as a bitmap on the PC, which has a high-power CPU and substantial memory resources, rather than generating PDL drawing commands and transferring the PDL drawing commands to the printer through a network and processing them on the printer.
Therefore, printer drivers provide a mode in which an entire page is rendered into a bitmap and transferred to a printer (hereinafter called raster mode) and allow manual or automatic selection between PDL mode and raster mode. A technique disclosed in Japanese Patent Laid-Open No. 2004-030386 reduces the number of PDL commands by temporarily storing drawing instructions provided from an OS and grouping neighboring drawing instructions into a PDL command in image data form. This technique has prevented reduction of performance by combining the advantages of PDL mode and image mode.
However, the method that provides the raster mode and allows a user to set the raster mode by means of a printer driver does not allow the user to determine whether PDL drawing commands will produce a huge amount of data. Consequently, in many cases, print processing in slow PDL mode is chosen. If the printer driver predicts which of the modes will process each page faster, one page of print data must be held and no print data is sent to the printer while the print data is held, increasing the first printout time. In addition, much PC resources are required.
On the other hand, the method described in Japanese Patent Laid-Open No. 2004-030386 solves the problem by converting only contiguous drawing instruction portions to image data and using PDL commands for the other portions. However, some recent applications use drawing instructions to use small images to draw only individual solid line portions of an apparently dashed line (see FIG. 4) or specify to use small images to draw only black pixels of a larger image (see FIG. 6). Because such disconnected images are not contiguous to one another, the images cannot be combined by using the method described in Japanese Patent Laid-Open No. 2004-030386, remaining to degrade performance.